Inception is a giant movie with a tiny, personal heart. Writer-director Christopher Nolan (The Dark Knight) may describe Inception as “a big action heist movie,” as he said in The New York Times, but when you peel back the countless layers, what sits quietly at the center of the film is a very human-sized handful of ideas about grief, loss, guilt, forgiveness and the propagation of ideas.

On the surface, Nolan’s description sums things up just fine: After a job goes awry, Dominic Cobb (Leonardo DiCaprio) — who claims to be the best there is at extracting secrets from the dreaming minds of men and women who don’t know they’re asleep — is offered an irresistible opportunity if he can perform the opposite task: plant an idea in the mind of a dreamer. It’s the mythic one-last-job of countless films about thieves and scoundrels, and in true heist fashion, Cobb must assemble his perfect team. He already has his point man, the sartorially admirable Arthur (Joseph Gordon-Levitt); he adds a chemist, Yussef (Dileep Rao), who creates the compounds that allow dreamers to share dreamscapes; a forger, Eames (a magnetic Tom Hardy, from Bronson), with extensive fakery skills; and a new architect, the aptly named Ariadne (Ellen Page), whose task it is to build carefully laid-out, finite dreamworlds. One person designs; another dreams; a third, the subject, fills the dream with his or her subconscious (neatly, the dreams always begin in the middle, as remembered dreams tend to do). It’s elegant but not simple — especially when inception, the planting of a viable idea, is the goal. “If we are going to perform inception,” Eames says, “we need imagination.”

The reverse-heist aspect is tense and effective. The crew delves into the mind of Robert Fischer (Cillian Murphy), who must get the idea to break up his father’s business empire. Ariadne’s dream levels are familiar, iconic, with room for avalanches, shootouts and a weightless sequence that’s a marvel of physical grace (on the part of Gordon-Levitt, who did most of the work himself) and clever filmmaking.

But one thing mars the dreamworld, no matter how carefully a dream is constructed: Mal (Marion Cotillard), Cobb’s projection of his wife. Why and how she’s there at first seems secondary to Inception’s interests. But Nolan carefully doles out information about Mal, her relationship with Cobb and Cobb’s relationship with the dreamworld, building a secondary narrative that begins to take over the film.

Inception is a gorgeous reflection on cinema: the creation of worlds intended to be shared, the emotions and ideas derived from a carefully crafted fictional narrative, the subconscious of the viewer filling the movies with meaning the filmmakers can only suggest, not outright supply. (It’s also got some of cinema’s classic flaws: The dialogue lands too heavily at times, and the bad guys have unaccountably awful aim.) But the self-aware meta-commentary of a movie about moviegoing is only one piece of what Inception offers. Its meanings are layered as carefully as the dream-within-a-dream-within-a-dream structure Cobb’s team uses to plant their idea in Fischer’s head. It’s a heist film, a film about filmmaking and a film about the things that we bring to stories — things that aren’t there until we read or watch or hear them. As Cobb creates an elaborate setup to put an idea in someone else’s mind, he allows something new to blossom in his own. Nolan concocts an even more elaborate narrative to explore an idea, and in the process involves the willing audience in the exploration of an idea — or several. Inception’s beautifully ambiguous, much-discussed ending isn’t a puzzle to solve, but a process, a question with no right answer, a dream for us to share.